Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
  • C04B28/04—Portland cements
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
  • C09K8/42—Compositions for cementing, e.g. for cementing casings into boreholes; Compositions for plugging, e.g. for killing wells
  • C09K8/46—Compositions for cementing, e.g. for cementing casings into boreholes; Compositions for plugging, e.g. for killing wells containing inorganic binders, e.g. Portland cement

Definitions

• the present invention broadly relates to well cementing. More particularly the invention relates to cementing compositions comprising a mixture of cellulosic polymer and AMPS monomer based polymer as well as methods for using such compositions to service a wellbore.
• Hydroxyethyl celluloses have been used for many years as fluid-loss control agents in oilwell cement slurries.
• various grades having different molecular weight and ethoxylation cover slightly different ranges of application in terms of temperature and slurry density. They all suffer from viscosifying and retarding too much the cement slurry, thus their use is limited to temperatures typically lower than 85°C and to lighter weight slurries.
• a low molecular-weight HEC is used as a fluid-loss control agent in cement slurries having a Solid Volume Fraction (SVF) of about 35% to about 60%.
• SVF Solid Volume Fraction
• a low/medium molecular-weight HEC is used as a fluid-loss control agent in cement slurries having a SVF of about 20% to about 30% (i.e., extended slurries). And a high molecular-weight HEC, is primarily used as an extender in extended cement slurries. Last one also provides some fluid-loss control.
• co- or ter-polymer containing AMPS and one or several vinyl or acrylic co-monomers like Acrylic acid, Methacrylic acid, Acrylamide, NN dimethylacrylamide, N vinylpyrrolidone, NN dimethylformamide, N-vinyl-N-methylacetamide, ACMO ].
• These synthetic polymers can be either long chain polymers or short-chain elements grafted onto a natural polymeric backbone (tannin, humic acid, causticized lignite%) for improving the ecotox properties.
• These synthetic polymers are much more expensive than the HEC derivatives and are supposed to provide fluid loss control at much higher temperatures. However some of these synthetic polymers also viscosify significantly the cement slurries, which limit seriously their temperature range. Other synthetic polymers on the other hand does induce severe slurry instability and particle settling.
• a cement slurry composition comprising an hydraulic cement, water and a combination made of a cellulosic polymer and an acrylamido-methyl-propane sulfonate co- or ter-polymer, wherein the density of said cement slurry is above 1700 kg/m 3 .
• the cellulosic polymer is a hydroxyethyl cellulose and/or the acrylamido-methyl-propane sulfonate copolymer is a acrylamido-methyl-propane sulfonate - acrylamide copolymer.
• This combination of polymers can be used with all Portland cements, whether ISO/API Class A, C, G and H cements or not, and with all types of pozzolanic or slag cements (Portland cement blended with pozzolanic materials such as fly ash, blast-furnace slag, calcined clay, diatomaceous earth, silica fume, microsilica... etc).
• pozzolanic or slag cements Portableland cement blended with pozzolanic materials such as fly ash, blast-furnace slag, calcined clay, diatomaceous earth, silica fume, microsilica... etc.
• Excellent performances can be obtained over a wide temperature range and wide slurry density range.
• the slurry has a density above 1800 kg/m 3 . More preferably, the density is between 1800 kg/m 3 to2050 kg/m 3 .
• the hydraulic cement is a pozzolanic cement.
• the system of the invention provides better fluid-loss control
• the hydroxyethyl cellulose has a molecular weight between 500,000 and 2,000,000 and preferably between 800,000 and 1,600,000, a concentration by weight of cement between 0.1 % to 0.8 % and the AMPS - Acrylamide copolymer has a molecular weight between 600,000 and 1,000,000, a concentration by weight of cement between 0.1 % to 1 %.
• the hydroxyethyl cellulose to acrylamido-methyl-propane sulfonate polymer ratio varies between 5:1 to 1:5.
• a method of cementing a well comprising the step of pumping a cement slurry as disclosed previously is divulged.
• the method can apply to well temperature varying between from 20°C to up to 150°C
• the method can further comprises the step of drilling the well and running a casing, wherein the step of cementing applies to cement the casing.
• the method can further comprises the step of drilling, and optionally casing, a first section of the well, optionally drilling a second section of the well, running a string of drill pipe or tubing and pumping a cement slurry as previously presented for curing losses.
• the method can further comprises the step of drilling, and optionally casing, a first section of the well, optionally drilling a second section of the well, running a string of drill pipe or tubing and pumping a cement slurry as previously presented for temporarily or permanently abandoning a zone.
• the method can further comprises the step of drilling and casing the various sections of a well, producing the fluids from a subterranean reservoir, and pumping a cement slurry as previously presented for abandoning the section once it is not economical anymore to produce.
• the method can further comprises the step of drilling and casing the various sections of a well, evaluating the isolation of the respective intervals, perforating the casing and running a string of drill pipe or tubing and pumping a cement slurry as previously presented for repairing a lack of isolation from the primary cementing operation.
• the cement slurry composition of the invention comprises: an hydraulic cement, water and a combination made of a cellulosic polymer and an acrylamido-methyl-propane sulfonate co- or ter-polymer, wherein the density of said cement slurry is above 1700 kg/m 3 .
• Hydraulic cements used can be ISO/API Class A, C, G and H cements.
• Pozzolanic cements are preferred (i.e., Portland cement blended with fly ash, calcined clay, blast-furnace slag, silica fume, or diatomaceous earth).
• Current invention is based on combination of two selected water-soluble polymers in a cement slurry allowing to decouple the slurry rheology from the fluid-loss rate, whilst bringing down significantly the overall cost of the slurry.
• the first polymer is a HEC, CMHEC, CMC, hydrophobically modified HEC, EHEC, MC, HPC, MHEC.
• the first polymer is a hydroxyethyl cellulose (HEC) of relatively high molecular weight around 1,200,000.
• the second polymer is an acrylamido-methyl-propane sulfonate co- or ter-polymer, taken in the non exhaustive list of: 2-acrylamido-2-methylpropane sulfonic acid/N,N-dimethylacrylamide/C 6 -C 22 dimethylaminopropylmethacrylamide bromide, chloride or iodide; 2-acrylamido-2-methylpropane sulfonic acid/acrylamide/ C 6 -C 22 dimethylaminopropylmethacrylamide bromide, chlorine or iodide; 2-acrylamido-2-methylpropane sulfonic acid/N-vinylpyrrolidone/ C 6 -C 22 dimethylaminopropylmethacrylamide bromide, chloride or iodide; 2-acrylamido-2-methylpropane sulfonic acid/N-vinylacetamide/ C 6 -C 22 dimethylaminopropylmethacryl
• the hydroxyethyl cellulose is at a concentration by weight of cement between 0.1 % to 0.8 % and the AMPS - Acrylamide copolymer is at a concentration by weight of cement between 0.1 % to 1 %.
• the total concentration of both polymers varies by weight of cement between 0.4 % to 1.6 %.
• the HEC to AMPS polymer ratio can vary between 5:1 to 1:5 depending on temperature.
• the cement slurry composition of the invention can further comprise other additional additives: antifoam, dispersant, retarder as required.
• the cement slurry composition of the invention can further comprise silica, preferably the silica is present in an amount of 35% BWOC.
• cement slurry composition of the invention are in the range of densities between 1700 kg/m 3 up to 2050 kg/m 3 .
• a method of cementing a well comprising the step of pumping a cement slurry as disclosed herewith.
• This combination of polymers can be used to cement a well with very wide range of temperatures: from 20°C to up to 150°C.
• the range of cementing temperatures applies not only from ambient to temperature around 100°C, but also to wells with higher cementing temperatures up to 150°C.
• Copolymers based on AMPS are well known fluid loss controlling additives used over wide range of temperatures in cement slurries for oil well cementing, particularly for temperatures above 93 degC and up to 149 degC. Since AMPS is an expensive monomer, cost of cement slurry increases significantly if AMPS co-polymers are used to control fluid loss. Apart from high cost, AMPS co-polymer that may be used at high temperatures, have another disadvantage which is their dispersing effect from 93 degC to 149 degC. If used alone, these AMPS polymers can cause severe sedimentation in the slurry and make cement slurry unstable. Therefore, most of the times, AMPS copolymers need antisettling agents to stabilize cement slurries.
• the principal objective of the invention is to minimize the cost without jeopardizing the fluid loss control property and eliminate or minimize the requirement for antisettling agent. Therefore, it has been proposed to blend very effective AMPS copolymer with HEC, where HEC acts as suspending agent whilst also controlling the fluid loss. Being a lower cost polymer, it helps bringing down significantly the overall cost of the slurry.
• HEC:AMPS copolymer (4:1) blend was prepared and tests were performed at temperatures ranging from 49 degC to 121 degC using Red Label class G cement from Dyckerhoff AG, tap water and other additives commercially available. Tests are presented in the following tables.
• Table 1 shows results with a slurry density of 1890 kg/m 3 made with Red Label class G cement from Dyckerhoff AG at 49 degC: Table 1 : Results at 49 degC
• Table A B C Antifoam agent (L/tonne) 0.45 0.45 0.45 HEC:AMPS copolymer %BWOC Blend 0.35 HEC (%BWOC) 0.45 AMPS copolymer (%BWOC) 0.25 Dispersant 1 (%BWOC) 0.4 0.15 0.3 PV (mPa.s) after mixing 264.5 96.6 120 Ty (Pa) after mixing 16.5 5.8 5.2 PV (mPa.s) after conditioning 157.2 74.1 81 Ty (Pa) after conditioning 6.7 4.6 2.9 Fluid Loss at 49 degC 46 54 52 Thickening Time 6:04 1 4:51 2 UCA 12 hrs CS 1006 UCA 24 hrs CS 2253
• HEC:AMPS copolymer blend had some advantages over HEC at 49 degC. Lower concentrations of Blend was required to obtain same level of fluid loss control, lower rheology and shorter thickening Time were obtained with HEC:AMPS copolymer blend (No over-retardation).
• Table 2 shows results with a slurry density of 1890 kg/m 3 made with Red Label class G cement from Dyckerhoff AG at 71 degC: Table 2 : Results at 71 degC Example D E F Antifoam agent L/tonne 0.45 0.45 0.45 HEC:AMPS copolymer %BWOC Blend 0.4 HEC (%BWOC) 0.6 AMPS copolymer (%BWOC) 0.35 Dispersant 1 (%BWOC) 0.4 0.25 0.3 Retarder 1 (%BWOC) 0.1 0.1 0.1 PV (mPa.s) after mixing 217 82.89 195 Ty (Pa) after mixing 30.1 1.05 10.5 PV (mPa.s) after conditioning 176 74.9 108 Ty (Pa) after conditioning 17 2.2 9.1 Fluid Loss at 71degC 60 56 56 Thickening Time (100 BC) 6:26 4
• Table 3 shows results with a slurry density of 15.8 lbs/gal (1890 kg/m 3 made with Cement Dyckerhoff Red Label at 85 degC: Table 3: Results at 85 degC
• Example G H Antifoam agent (L/tonne) 0.45 0.45 HEC:AMPS copolymer Blend (%BWOC) 0.5 HEC (%BWOC) AMPS copolymer (%BWOC) 0.45 Dispersant 1 (%BWOC) 0.35 0.2 Retarder 2 (%BWOC) 0.2 0.2 PV (mPa.s) after mixing 101.9 253 Ty (Pa) after mixing 3.7 16.2 PV (mPa.s) after conditioning 78.7 95 Ty (Pa) after conditioning 2.7 7.2 Fluid Loss at 85 degC 56 54 TT (100BC) 3:25 CS 12 hrs (MPa) 12.17 CS 24 hrs (MPa) 16.8
• Table 4 shows results with a slurry density of 1890 kg/m 3 made with Red Label class G cement from Dyckerhoff AG at 110 degC: Table 4 : Results at 110 degC
• HEC alone could not be used as fluid loss control additive.
• Slurry prepared with AMPS copolymer alone was good at controlling fluid loss with good rheology.
• HEC:AMPS copolymer blend was tested with and without sodium silicate and different behavior was observed. With sodium silicate, lower amount of blend was required to control the fluid loss and slurry was very cost effective. Without addition of sodium silicate, HEC:AMPS copolymer blends needed to be complemented with 0.1 %bwoc of AMPS copolymer to get same level of fluid loss.
• slurry prepared with AMPS copolymer was 20% more expensive than slurry prepared with HEC:AMPS copolymer blend with silicate additive. And slurry with HEC:AMPS copolymer blend without silicate additive was 10% more expensive than slurry with silicate additive.
• Table 5 shows results with a slurry density of 1890 kg/m 3 made with Red Label class G cement from Dyckerhoff AG at 121 degC: Table 5: Results at 121 degC

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• 2008
  • 2008-07-24 EP EP08290728A patent/EP2147902A1/de not_active Withdrawn
• 2009
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